UGT1A1 and Decreased total neutrophil count: Previous studies have found that at the same dose of CPT-11, patients with genetic mutations of UGT1A1*28 and UGT1A1*6 might face increased risk of neutropenia and diarrhea, especially in patients with homozygous mutations of UGT1A1*28 and UGT1A1*6, and in that case the dose of CPT-11 needs to be reduced.